"""
选择：
1.c 2.b 3.d 4.a 5.a 6.c
填空:
1.s = hello world
  d  llo   hlod    lrowolleh
2.s.upper = PYTHON STRING
  s.lower = python string
  s.find  = 10
  s.repla = PYthon strgni








"""
s='PYthon String'
s.replace('ing','gni')
print(s.replace('ing','gni'))